450 



PRIMORDIAL GROUP OP BOHEMIA. [Ch. XXVII 



Bohemia. — M. Barrande, in his admirable monograph on the Paleozoic 

 rocks of Bohemia, has laid much stress on the distinctness and isolation 

 of what he calls the "Protozoic schists," which attain a thickness of 1200 

 feet, and lie at the base of the whole Silurian group, as defined by him ; 

 These schists have no limestone associated with them, and are regarded 

 by M. Barrande as contemporaneous with the " Lingula Flags" of N. 

 Wales. So far as he has yet carried his researches, this " primordial 

 fauna," as he designates it, has yielded scarcely any other fossils than 

 Trilobites, the other animal remains consisting of a Pteropod, some Cys- 

 tideee, and an Or this, all of new and peculiar species. Of the Trilobites, 

 even the genera, with the exception of one {Agnostus, figs. 615 and 616), 

 are peculiar. These genera are Paradoxides (see fig. 613), of which 

 there are no less than twelve species, Conocephalus (fig. 614), Ellipso- 



Fossils of (he lowest Fossiliferous Beds in Bohemia, or " Primordial Zone " of Barrande. 

 Fig.J13. Fis. (514. 



Conocephalux striatus, Emmrich. 



i nat. size. 



Ginetz and Skrey. 



Paradoxides Bohemians, Barr. 



About one-third natural size. 



" Lowest Silurian' Beds " of 



Ginetz, Bohemia. 



(Etage C. of Barrande.) 



Fig. 61T. 



Fig. 615. 



Agnostus integer, Beyrich. 

 Nat size and magnified. 



Fig. 616. 



Agnostus Bex, Barr. 

 Nat. size, Skrey. 



cephalus, Sao (fig. 617), Arionellus, and 

 Hydrocephalus. They have all a facies of 

 their own, dependent on the multiplication 

 of their thoracic segments, and the dimi- 

 nution of their caudal shield or pygidium. 

 All the Bohemian species differ as yet 

 from any found in England, which may 

 be owing chiefly to the very small num- 

 ber as yet known in Great Britain ; or it 

 may be due entirely to the influence of 

 segments begin to be developed; fo geographical causes. It seems, neverthe- 



tbe stage a the eyes aro introduced, & & r ' 



but the facial sutures are not com- i ess to confirm the view here taken of the 



pleted ; at e the full-grown animal, half . _ . . 



its true size, is shown. " primordial zone being characterized 



by fossils distinguishable from the Llandeilo, or Lower Silurian group ; 

 because the other and higher Silurian formations of Barrande have each 

 of them many species in common with the successive subdivisions of the 

 British series. 



Sao hirsuta, Barrande, in its various 

 6tages of growth. Skrey. 



The small lines beneath indicate the 

 true size. In the youngest state, a, 

 no segments are visible ; as the meta- 

 morphosis progresses, b, c, the body 



